What were the top predators in North and South America?

[Earl_Snake-Hips_Tucker]

Back in the old-timey days when *South America and North America were still islands. I think the predators that we think of today (cats, dogs, bears, etc.) came over courtesy of the land bridge with Asia. If I’m wrong, please set me straight. If not, what savage animal was at the top of the food chain on those respective (and very big) islands.

*After SA had separated from Africa, and NA had separated from “Europe” and had not yet “connected” with eastern “Asia.”

[Q.E.D]

The top predador when humans first occupied North America was undoubtedly the saber-toothed cat.

[Ice_Wolf]

The Panamanian Gap was finally bridged around 3.5 million years ago. Up until that time, “true” carnivores didn’t exist in South America, according to this page:

The first larger sparassodonts are known from the middle Paleocene of Brazil. They include the medium sized genus Patene (meaning ‘fox’ in a native South American language) and a poorly known wolf-sized predator. These marsupial carnivores developed basically the same tooth structure for cutting meat as the true (placental) carnivores of the northern hemisphere. Unlike true carnivores, however, sparassodonts did not develop particular adaptations for fast running. This may have been one reason for their decline and finally their extinction after the arrival of true carnivores in South America in late Cenozoic time.

In North America, it could well have been ancestors of the sabretooth cats which were supreme before the gap closed.

[Lemur866]

Before the panama land bridge formed, South America had a completely different set of animals. South America had been an island continent since the extinction of the dinosaurs. There were marsupials (like the oppossum), xenarthrans (armadillos, sloths, and anteaters), rodents (many giants, like the capybaras, porcupines, guinea pigs, etc.), monkeys, and many species of notungulates…South American ungulates completely unrelated to artiodactyls or perrisodactyls and coming in all shapes and sizes.

Probably the largest predator was Thylacosmilus, a gigantic marsupial with huge sabre teeth, convergent with the placental Smilodon of North America although of course completely unrelated. If you are interested in South American mammal evolution, GG Simpson’s book “Splendid Isolation” is a great place to start.

[Spoke]

North America also had some nasty crocodilians.

Not sure about S.A. (?)

Also, let us not forget the anaconda in S.A.

[Earl_Snake-Hips_Tucker]

I’d suspect that the terror birds were close to the top in SA, also.

However. . .

That still leaves the question about NA, before the cats arrived. I don’t think they were native to North America, but immigrants from Asia.

[Lemur866]

The trouble is that NA was never as isolated as SA. Immigrants from Asia and Europe arrived every so often depending on sea levels.

OK, but you are interested in pre-cat times, so we just have to figure out the first recorded cats in NA, and find out some large NA predators from that time. I’ll have to wait till I get home…

[Polycarp]

The borhyaenids, a group of marsupial carnivores, were the dominant quadrupedal South American predators during the later Tertiary. I presume the sparassodonts are more or less synonynous with them (either a direct synonym or one being a subset of the other).

During Paleocene and Eocene times, South America had perhaps the last major archosaur land predators – the sebecosuchids, long-legged, deep-and-narrow-headed crocodiles adapted for land carnivory. Later the dominant predators were phorusrhacids, giant crane-like birds that held even the borhyaenids at bay and were quite capable of taking down a litoptern.

AFAIK North American Tertiary carnivores were variations on the standard issue – canoids and feloids, along with raptors (the birds, not the dinosaurs).

[Earl_Snake-Hips_Tucker]

OK, I think I have some contenders for North American predators: Patriofelis and Mesonyx.

Source: “Thread of Life” by Roger Lewin

[astro]

You’re all forgetting about the age of the terror birds when they ruled south america for millions of years as the top predator.

Terror Birds
Standing up to 3 metres tall, with a powerful hooked beak, Andalgalornis and its relatives were truly ‘Terror-birds’. these large, flightless birds roamed the South American grasslands between 2 and 62 million years ago - their closest living relatives are the cranes and rails, including the decidedly un-terrifying moorhen. they had strong, powerful legs and could probably run at speeds of up to 40 miles per hour, chasing down the early mammals which were their prey. Among the top predators of their day, they finally died out as the climate warmed, and their grassland habitat was replaced with dense tropical forest.

Andalgalornis
Explorer

These days, a trip across the Argentine pampas can be rather dull. But in the Cenozoic period it was a different story. In those days, terror birds ruled the continent-- a family of birds known as Phorusrachids that grew to gigantic proportions. The terror bird that roamed Argentina was the Andalgalornis.

Phorusrachids were, by most accounts, the most formidable predators in South America and reigned supreme for millions of years, stalking the grasslands in search of prey. With their massive blade-like beaks, an Andalgalornis could slice through the flesh and bones of its victim.

Other terror birds are believed to have developed a modified inner toe with a large claw, a lethal weapon against any of the larger mammals they encountered.

Terror birds such as the Andalgalornis died out some 2.5 million years ago after the Panamanian land bridge linked North and South America. By some accounts, large cats came down from the North and ended the reign of terror.

More about terror birds can be found in an upcoming issue of the South American Explorer with a sidebar by Stacey Burgess, the recreator of the Andalgalornis (shown here) and other prehistoric creatures.

[astro]

“You’re all forgetting about the age of the terror birds when they ruled south america for millions of years as the top predator.”

Except Earl Snake-Hips Tucker :o

[Polycarp]

*Originally posted by astro *
**“You’re all forgetting about the age of the terror birds when they ruled south america for millions of years as the top predator.”

Except Earl Snake-Hips Tucker :o **

Astro, it was I (it was me?) who beat you to the Phorusrhacids – though you did a beautiful job on it, with cites!

Unless you mean that they were the top South American predator except for Earl! (Those snake-hips probably come in handy when chasing down prey! :D)

For North America, it all depends on what point in the Tertiary you’re talking about. There were a lot of different creodonts and carnivores across the 64 million years of the Tertiary Period. While within its limited niche Smilodon was probably the top predator, the American lion (a distinct subspecies of good old Panthera leo) and the dire wolf (Canus dirus), a pack-hunting animal about the size of a tiger (but taller, because longer legs), would also be important predators, and probably the more common.